An opening and closing mechanism for opening and closing bodies for opening and closing a plurality of opening and closing bodies (for example, shoji, doors, etc.) is known. Patent Document 1 discloses a sliding door device as an example of such an opening and closing mechanism for opening and closing bodies. This sliding door device comprises a running body running in the right and left directions, a left guide body and a right guide body which are mounted on the running body rotatably in the left and right directions, a sliding door mounting body having a left roller running along the left guide body and a right roller running along the right guide body, a sliding door mounted on the sliding door mounting body, and a biasing means provided between the running body and the sliding door mounting body and biasing the sliding door mounting body backward. This sliding door device assures that a smooth movement of the sliding door mounting body can be achieved and operability of the sliding door can be improved.